[RFC PATCH v2 06/23] sched/topology: Add sd_node for the NODE sched domain

[Jianyong Wu]

There is no straightforward way to retrieve the NODE-level sched domain,
which will be used in subsequent patches. To simplify this, add a per-CPU
variable `sd_node` for convenience.

Signed-off-by: Jianyong Wu <wujianyong@xxxxxxxx>
---
 kernel/sched/sched.h    |  1 +
 kernel/sched/topology.c | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 38453a78c885..3d3f1d40a672 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2197,6 +2197,7 @@ DECLARE_PER_CPU(int, sd_llc_id);
 DECLARE_PER_CPU(int, sd_share_id);
 DECLARE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 DECLARE_PER_CPU(struct sched_domain_shared __rcu *, sd_balance_shared);
+DECLARE_PER_CPU(struct sched_domain __rcu *, sd_node);
 DECLARE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 DECLARE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index eaaca6c9a805..46ae1f94e9f5 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -679,6 +679,7 @@ DEFINE_PER_CPU(int, sd_llc_id) = -1;
 DEFINE_PER_CPU(int, sd_share_id);
 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_llc_shared);
 DEFINE_PER_CPU(struct sched_domain_shared __rcu *, sd_balance_shared);
+DEFINE_PER_CPU(struct sched_domain __rcu *, sd_node);
 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_numa);
 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_packing);
 DEFINE_PER_CPU(struct sched_domain __rcu *, sd_asym_cpucapacity);
@@ -721,6 +722,19 @@ static struct llc_local_rank_topology __rcu *llc_local_rank_topo;
 static void rebuild_llc_local_rank(int size);
 #endif
 
+/* Get sched domain by its name */
+static struct sched_domain *get_sched_domain_by_name(int cpu, char *name)
+{
+	struct sched_domain *sd = NULL;
+
+	for_each_domain(cpu, sd) {
+		if (!strcmp(sd->name, name))
+			break;
+	}
+
+	return sd;
+}
+
 static void update_top_cache_domain(int cpu)
 {
 	struct sched_domain_shared *sds = NULL;
@@ -753,6 +767,9 @@ static void update_top_cache_domain(int cpu)
 	 */
 	per_cpu(sd_share_id, cpu) = id;
 
+	sd = get_sched_domain_by_name(cpu, "NODE");
+	rcu_assign_pointer(per_cpu(sd_node, cpu), sd);
+
 	sd = lowest_flag_domain(cpu, SD_NUMA);
 	rcu_assign_pointer(per_cpu(sd_numa, cpu), sd);
 
-- 
2.34.1